CAT - CSS Animation Timeline
Set of AngularJS directives to simplify development and composition of animations on static websites.
Why
Most modern "static" websites, have loads of complicated animations, often built out of smaller bits. You need to sequence CSS transition, CSS animations and custom javascript stuff, manage scroll-based trigger, make those repeatable.
You don't wont to stick all this complexity in a controller which not only shouldn't be there just because of animations, you'll also end up having code duplication and find yourself in a code maintenance hell.
The solution
A set of
- Declarative
- Reusable
- Composable
- Nestable
AngularJS directives!
Components
cat-scroll-container and cat-visible directives
Detect when an element is fully visible (and fully hidden) in page, and sets a scope variable accordingly
[...] When I'm visible, `runAnimation` is set to true [...]At the moment, these work only when there are no "nested" scrolling container.
cat-class directive
Play/stop CSS based animation using a --start class modifier.
I am a red text!Toggle statusThe fact that animations are defined "backward", makes it way easier to write CSS
for browser where you don't wont animations to run (mobile, legacy). The final status
of the animation is defined by its default style (.a-class-name), while the
--start version specifies how to set up the animation.
Note that we use transition: none to avoid running the transition "backward", when resetting it (but we could, if we wanted to!)
cat-delay directive
Introduce a delay in an animation sequence. This is particularly useful when you're sharing sub-animations and you need to fine tune delays on a per-case scenario.
cat-timeline directive
Combine all its children directive and, (if cat-active is set) runs them in
sequence.
This is where most of the magic happens. You can use the timeline to play a sequence of simple animations, nest them, or run them in whatever order you want!
By default, the animations are run in sequence, and not repeated unless cat-undo is specified.
APIs
All directives can be controlled both declarative, via HTML attributes, or programmatically, by requiring their angular controller.
For most use cases, HTML attributes should be enough. You should care about the programmatic interface only if you're writing custom directives that needs to integrate with the timeline (or if you're contributing to this project!)
Shared HTML interface
cat-active
Used to trigger the animation when changes to true. It should be used as a "read only" scope variable by the animation directives and set from the outside (e.g. by cat-visible).
cat-undo
Default: false
Tells the directive that the animation should be "cleared" (resetted) when cat-active switches back to false
cat-animation-name
Defaults to the directive name
Name to be used when registering the animation on the parent cat-timeline.
cat-status
Read-only variable (written by the directives). Can be used to check the animation status. Can be 'READY', 'RUNNING', 'CLEARING' or 'FINISHED'. Very useful if you want to play animations only when other are finished, but don't or can't create a "global" animation for all of them.
Additional HTML APIs
Not shared among all directives
cat-class="<class-name>"
Tells the directive to use <class-name> as CSS animation class: this will make the animation
add a <class-name>--start class to set-up the animation.
cat-delay="<millis>"
How long to wait, in milliseconds.
Shared JS interface
controller.play() : Promise
Start the animation and returns a promise, resolved when the animation is over. If called when the animation is already running, the same promise is returned.
controller.clear() : Promise
Reset the animation to its initial state, returning a promise resolved when the clearing operation is finished.
Additional JS APIs
timelineController.register(animationName: string, animationController [, order: number])
Called by "component" directives to register themselves. The order parameter is currently only available via JS APIs, but will be added as a shared attribute in the future.
timelineController.get() //TODO
Not implemented yet, should allow to get a children animation from the controller for custom animation ordering and sequencing (e.g. first two in parralle, than the third, than another two...)